We are studying methods that may facilitate direct gene transfer into muscle. Intramuscular injections of plasmid DNA has been shown to express transgenes at relatively efficient levels. Experiments are currently underway to define the mechanism of DNA uptake by muscle cells. We would like to use the confocal microscope to examine the efficiency of nuclear uptake of DNA under various conditions after cytoplasmic microinjection. The confocal n-dcroscope is necessary to determine the exact location of injected DNA, i.e. inside or outside of the nucleus. We will also be testing other techniques for gene introduction such as digitonin permeabilization and in vitro transfection.